• Journal of Bio-Environment Control
• /
• v.20 no.2
• /
• pp.93-100
• /
• 2011

Maintenance of adequate soil water potential during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement within and below the rooting zone can facilitate optimal irrigation scheduling aimed at minimizing the adverse effects of water stress on crop growth and development and the leaching of water below the root zone which can have adverse environmental effects. The objective of this study was to evaluate the feasibility of using a portable irrigation controller with an Watermark sensor for the cultivation of drip-irrigated vegetable crops in a greenhouse. The control capability of the irrigation controller for a soil water potential of -20 kPa was evaluated under summer conditions by cultivating 45-day-old tomato plants grown in three differently textured soils (sandy loam, loam, and loamy sands). Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30 cm depths. Even though a repeatable cycling of soil water potential occurred for the potential treatment, the lower limit of the Watermark (about 0 kPa) obtained in this study presented a limitation of using the Watermark sensor for optimal irrigation of tomato plants where -20 kPa was used as a point for triggering irrigations. This problem might be related to the slow response time and inadequate soil-sensor interface of the Watermark sensor as compared to a porous and ceramic cup-based tensiometer with a sensitive pressure transducer. In addition, the irrigation time of 50 to 60 min at each of the irrigation operation gave a rapid drop of the potential to zero, resulting in over irrigation of tomatoes. There were differences in water content among the three different soil types under the variable rate irrigation, showing a range of water contents of 16 to 24%, 17 to 28%, and 24 to 32% for loamy sand, sandy loam, and loam soils, respectively. The greatest rate increase in water content was observed in the top of 10 cm depth of sandy loam soil within almost 60 min from the start of irrigation.

• Journal of Mushroom
• /
• v.12 no.3
• /
• pp.209-215
• /
• 2014

Changes in physical and chemical properties of oak sawdust were investigated by depth and time for 46 days during the fermentation process of 33 tons of the sawdust for oak mushroom cultivation. The degrees of change in the properties of the sawdust differed depending on the depth and fermentation period. Most of the physical-chemical properties except temperature and pH gradually changed during the fermentation. The temperature change was highly sensitive to the environment at the surface sawdust to 20 cm depth, while it gradually increased to the maximum $58.9^{\circ}C$ at 40~100 cm depths in 12 days and slowly to the maximum at 150 cm depth in 24 days. The moisture content of the sawdust decreased gradually from 31% to 26.5~28.0% in 24 days. Of the chemical properties during the fermentation, pH generally rose from 5.2 to 5.6, but it decreased to 4.4~4.7 at 150 cm depth in 16 days. While the carbon content of the sawdust was 68~70% without significant change, nitrogen content increased from 0.22% to 0.25% and thus C/N ratio gradually lowered from 320 to 280. P content in the sawdust gradually increased from 0.005% to 0.022% for 46 days. Osmotic concentration of the hot water extract of the sawdust varied 41.5~44.2 mmol/kg without significant change by the depth and time. The starch particles within initial ray parenchyma cells of sawdust decreased and fungal hyphae formed on the surface of the sawdust granules and within xylem vessel cells in 35 days. The effect of the sawdust fermentation on oak mushroom cultivation needs continued research.

• Development and Reproduction
• /
• v.13 no.2
• /
• pp.105-114
• /
• 2009

Ethane 1,2-dimethane sulfonate (EDS) is a well-known alkylating agent used as selective Leydig cell (LC) toxicant to create a testicular dysfunction model. Previous studies including our own clearly demonstrated the dramatic weight loss of the androgen dependent accessory sex organs such as epididymis, seminal vesicle and prostate gland in this 'LC knock-out' rats. The present study was performed to evaluate the effect of EDS administration on histological changes of the epididymis, seminal vesicle and prostate in adult rats. Adult male Sprague-Dawley rats (350$\sim$400 g B.W.) were injected with a single dose of EDS (75 mg/kg, i.p.) and sacrificed on weeks 0, 1, 2, 3, 4, 5, 6 and 7. Tissue weights (testis, epididymis, seminal vesicle and prostate gland) were measured. The histological changes of tissue were observed by a light microscopy using hematoxylin & eosin staining. Weights of the reproductive and accessory organs progressively declined after the EDS treatments (weeks 1, 2 and 3). After this, the decrease was stopped, then gradually returned to the normal levels. There was a partial (about 60%) recovery of the epididymis weight during weeks $6{\sim}7$. The cross section of epididymis revealed an increase in thickness of the epithelium during weeks $1{\sim}3$. In contrast, considerable reduction of epithelial thickness in seminal vesicle was observed during same period. Similarly, a reduction in thickness of prostate epithelial layer was found during weeks $1{\sim}3$, then it was back to normal thickness after week 4. Taken together, the present study demonstrated that the temporally induced androgen-deficiency by EDS treatment could result the prominent alterations in histology of the accessory sex organs. Further studies on the physiological and molecular regulation of these androgen-sensitive organs using EDS model will be helpful to understand the normal and pathological development and differentiation mechanism of these organs.

• The Korean Journal of Pesticide Science
• /
• v.11 no.4
• /
• pp.246-253
• /
• 2007

The reproduction toxicity of several pesticides on two Korean water flea was investigated to develop a new standard species used for ecological risk assessment of pesticide. Moina macrocopa and Daphnia sp. were exposed to 4 different types of pesticides over 10 and 21 days, respectively. No-ohserved effect concentration (NOEC) for synthetic pyrethroid, fenpropathrin on Moina macrocopa and Daphnia sp. were 0.17 and $0.06\;{\mu}g\;L^{-1}$, respectively. Diazinon, carbofuran and myclobutanil were in the order of their reproduction toxicity to cladocerans tested. There were large differences between Moina macrocopa and Daphnia sp. in their susceptibility to fenpropathrin, diazinon and carbofuran except myclobutanil. Daphnia sp. is more sensitive than M. macrocopa to pesticides tested. Therefore Daphnia sp. may be a good surrogate species to assess the reproduction effect of pesticides on aquatic invertebrates. M. macrocopa also be a good surrogate species because it is one of the most abundant cladocera in agricultural environment, especially rice paddy in Korea. In addition to it's ecological importance of wide spread distribution, it has also economical importance to make possible to shorten period for reproduction test using M. macrocopa due to it's short life cycle.

• The Korean Journal of Pesticide Science
• /
• v.12 no.1
• /
• pp.82-87
• /
• 2008

Algae are vital in the primary production of the aquatic ecosystem, having been considered as good indicators of the bioactivity of pesticides. Algae have short life cycle, respond quickly to environmental change and their diversity and density can indicate the quality of their habitat. The purpose of the study was to determine the growth inhibition effects of butachlor (Tech. 93.4%) and $K_2Cr_2O_7$ (Tech. 99.5%) in Selenastrum capriconutum, Scenedesmus subspicatus, Chlorella vulgaris and Nitzschia palea during and exposure period of 72 hours. The toxicological responses of S. capriconutum, S. subspicatus, C. vulgaris and N. Palea to butachlor, expressed in individual $ErC_{50}$ values were 0.0022, 0.019, 8.67 and $4.94\;mg\;L^{-1}$, respectively. NOEC values were 0.0008, 0.0016, 5.34 and $2.92\;mg\;L^{-1}$, respectively. S. capriconutum was more sensitive than the other algae species. The toxicological responses of S. capriconutum, S. subspicatus, C. vulgaris and N. palea to $K_2Cr_2O_7$ expressed as $ErC_{50}$ values were 0.91, 0.78, 0.85 and $0.57\;mg\;L^{-1}$, respectively. NOEC values were 0.2, 0.2, 0.2 and $0.18\;mg\;L^{-1}$, respectively. Growth inhibition of S. capriconutum, S. subspicatus, C. vulgaris and N. palea from PEC of butachlor were 100, 75, 0 and 0%, respectively.

• Korean Journal of Agricultural Science
• /
• v.8 no.1
• /
• pp.90-96
• /
• 1981

To design more efficient agricultural machinery, the accurately measuring system among many other factors is essential. A light-beam oscillographic recorder is generally used in measuring dynamic strain but it is not compatible with the extremely high speed measuring system such as 1,000 m/s, also is susceptable to damage due to vibration while using the system in field. The recorder used light sensitive paper for strip chart recording. The reading and analysis of data from the strip charts is very cumbersome, errorneous and time consuming. A microcomputer was interfaced with A/D converter, microcomputer program was developed for measuring, system calibration was done and the strain generated from a cantilever beam vibrator was measured. The results are summarized as follows. 1. Microcomputer program was developed to perform strain measuring of agricultural machine elements and could be controled freely the measuring intervals, no. of channels and no. of data. The maximum measuring speed was $62{\mu}s$. 2. Calibration the system was performed with triangle wave generated from a function generator and checked by an oscilloscope. The sampled data were processed using HP 3000 minicomputer of Chungnam National University computer center the graphical results were triangle same as input wave and so the system have been out of phase distorsion and amplitude distorsion. 3. The strain generated from a cantilever beam vibrator which has free vibration period of 0.019 second were measured by the system controlled to have l.0 ms of time interval and its computer output showing vibration curve which is well filted to theoretical value. 4. Using microcomputer on measuring the strain of agricultural machine elements could not only save analyzing time and recording papers but also get excellent adaptation to field experiment, especially in measurement requiring high speed and good precision.

• Journal of Korean Academy of Nursing
• /
• v.24 no.3
• /
• pp.413-431
• /
• 1994

The purpose of this study was to build a substantive theory about the experience of the family whose child has died of cancer The qualitative re-search method used was grounded theory. The interviewees were 17 mothers who had cared for a child who had died of cancer Traditionally in Korea, mothers are the care givers in the family and are considered sensitive to the family's thoughts, feelings. The data were collected through in-depth interviews by the investigator over a period of nine months. The data were analyzed simultaniously by a constant comparative method in which new data are continuously coded into categories and properties according to Strauss and Corbin's methodology. The 16 concepts which were found as a result of analyzing the grounded data were, -left over time, the empty place, meaninglessness, inner sadness, situational sadness, heartache, physical pain, guilt, resentment, regret, support / stigmatization, finding meaning in the death, changing attitudes about life and living, changing attitudes about health, changing religious practice and changing family relations. Five categories emerged from the analysis. They were emptiness, consisting of left over time, the empty place and meaninglessness ; sadness, consisting of inner sadness and situational sadness ; pain, consisting of heartache and physical pain ; bitterness, consisting of guilt, resentment, regret, sup-port / stigmatization and finding meaning in the death : and transition, consisiting of changing attitudes about life and living, changing attitudes about health, changing religious practice and changing family relations. These categories were synthesized into the core concept, -the process of filling the empty space. The core phenomenon was emptiness. Emptiness varied with the passing of time, was perceived differently according to support / stigmatization and finding meaning in the death, was followed by sad-ness, pain, and bitterness, and finally resulted in changes in attitudes about life and living and about health, and in changes in religious practice and family relations. The process of filling the empty space proceeded by ① accepting realty, ② searching for the reason for the child's death, ③ controlling the bitter feelings, ④ reconstructing the relationships ameng death, illness and health and ⑤ filling the emptiness by resolving causes of child's death, adopting, having another child or with work. Six hypotheses were derived from the analysis. ① The longer the bereavement, the mere the empty space becomes filled. ② The longer the hospitalization, the more sup-port the family needs. ③ The more the sadness, pain and bitterness are expressed, the mere positive changes emerge. ④ Family support faciliates the process of filling the empty space. ⑤ Higher family cohesiveness faciliates the process of filling the empty space. ⑥ The greater the variety of reasons attributed to the child's death, the greater the variety of patterns of change. Four propositions related to emptiness and bitter-ness were developed. ① When the sense of emptiness is great and bitterness is manifested by severe feelings of guilt and resentment, the longer the process of fill-ing the empty space. ② When the sense of emptiness is great and the family is highly motivated to get rid of the bitterness, the shorter the process of filling the empty space. ③ When the sense of emptiness is less and bitter-ness is manifested by severe feelings of guilt and resentment, the process of filling the empty space is delayed. ④ When the sense of emptiness is less and the family is highly motivated to get rid of the bitterness, the process of filling the empty space goes on to completion. Through this substantive theory, nurses under-stand the importance of emptiness and bitterness in helping the family that has lost a child through cancer fill the empty space. Further research to build substantive theories to explain other losses may con-tribute to a formal theory of how family health is restored after human tragedies are experienced.

• Korean Journal of Ecology and Environment
• /
• v.38 no.3 s.113
• /
• pp.361-371
• /
• 2005

The objective of study was to diagnose integrative ecological health of Daejeon Stream, one of the tributaries of Guem River, during May 2004 ${\sim}$ April 2005. The research approach was primarily based on a Qualitative Habitat Evaluation Index (QHEI) and the Index of Biological Integrity (IBI) using fish assemblage. These outcomes were compared with conventional chemical dataset. For the experiment, four sampling sites were chosen from Daejeon Stream and long-term water quality data during 1995 ${\sim}$ 2004 (obtained from the Ministry of Environment) were analyzed in the spatial and temporal aspects. For the biological health assessment, we developed a stream health assessment model (SHA model) far regional applications. We found that current water quality conditions, based on the COD, BOD, TN and TP, were enhanced by 1.6 ${\sim}$ 5.3 fold over the period of 1995 ${\sim}$ 2004 and that the parameters showed a typical longitudinal decline from the upstream to downstream reach. The differences of water quality between the two reaches were more than 4.4 times, indicating a large spatial variations within the stream. The health conditions, based on the SHA model, averaged 23 and varied from 20 to 26 depending on the sampling stations. Values of the QHEI varied from 39 (Poor condition) to 124 (Cood condition)and values of QHEI in the reach of S2 ${\sim}$ S4 had significantly lower than in the headwater site (S1). Also, biological stream health, based on the criteria of US EPA (1993), was judged as 'Poor condition', in the S4 where TN, TP, BOD and COD were highest. In the meantime, maximum value of SHA (26) was found in the upstream reach (S1) where the water quality and QHEI were best. We also found that compositions of sensitive species showed a linear function with water quality conditions and this pattern was evident in the tolerant species. Thus, the biological stream health, based on the SHA model, matched well water chemistry. Overall outcomes suggest that the biological health impact was a function of chemical degradation and physical habitat quality in the stream.

• Korea journal of population studies
• /
• v.9 no.1
• /
• pp.41-53
• /
• 1986

The purpose of this paper is two-fold. One is to investigate the determinants of the demand supply of labor, and another is to project long-term demand and supply of labor. The paper consists of three parts. In the first part, theoretical models and important hypotheses are discussed: for the case of a labor supply model, issues regarding discouraged worker model, permanent wage hypothesis, and relative wage hypothesis are examined and for the case of a demand model, issues regarding estimating an employment demand equation within the framework of an inverted short-run produc- tion function are inspected. Particularly, a theoretical justification for introducing a demographic cohort variable in a labor supply equation is also investigated. In the second part, empirical results of the estimated supply and demand equations are analyzed. Supply equations are specified differently between primary and secondary labor force. That is, for the case of primary labor force groups including males aged 25 and over, attempts are made to explain the variations in participation behavior within the framework of a neo-classical economics oriented permanent wage hypothesis. On the other hand, for the case of females and young male labor force, variations in participation rates are explained in terms of a relative wage hypothesis. In other words, the participation behavior of primary labor force is related to short-rum business fluctuations, while that of secondary labor force is associated with intermediate swings of business cycles and demographic changes in the age structure of population. Some major findings arc summarized as follows. (1) For the case of males aged 14~19 and 2O~24 groups and females aged 14∼19, the effect of schhool enrollment rate is dominant and thus it plays a key role in explaining the recent declining trend of participation rates of these groups. (2) Except for females aged 20∼24, a demographic cohort variable, which captures the impact of changes in the age structure on participation behavior, turns out to show positive and significant coefficients for secondary labor force groups. (3) A cyclical variable produce significant coefficients for prime-age males and females reflecting that as compared to other groups the labor supply behavior of these groups is more closely related to short-run cyclical variations (4) The wage variable, which represents a labor-leisure trade-off turns out to yield significant coefficients only for older age groups (6O and over) for both males and females. This result reveals that unlike the experiences of other higer-income nations, the participation decision of the labor force of our nation is not highly sensitive with respect to wage changes. (5)The estimated result of the employment demand equation displays that given that the level of GNP remains constant the ability of the economy to absord labor force has been declining;that is, the elasticity of GNP with respect to labor absorption decreasre over time. In the third part, the results of long-term projections (for the period of 1986 and 1995) for age-sex specific participation rates are discussed. The participation rate of total males is anticipated to increase slightly, which is contrary to the recent trend of declining participation rates of this group. For the groups aged 25 and below, the participation rates are forecast to decline although the magnitude of decrease is likely to shrink. On the other hand, the participation rate of prime- age males (25 to 59 years old) is predicted to increase slightly during 1985 and 1990. For the case of females, except for 20∼24 and 25∼34 age groups, the participation rates are projected to decrease: the participation rates of 25∼34 age group is likely to remain at its current level, while the participation rate of 20∼24 age group is expected to increase considerably in the future (specifi- cally, from 55% in 1985 to 61% in 1990 and to 69% in 1995). In conclusion, while the number of an excess supply of labor will increase in absolute magnitude, its size as a ratio of total labor force is not likely to increase. However, the age composition of labor force is predicted to change; that is, the proportion of prime-age male and female labor force is projected to increase.

• Pediatric Infection and Vaccine
• /
• v.5 no.2
• /
• pp.221-229
• /
• 1998

Purpose : The symptom of urinary tract infection in children is non-specific and systemic compared to that of adults. So the diagnosis of UTI in children can be delayed. If UTI in children is not appropriately managed, it may he resulted in renal failure, hypertension, growth failure in adolescence because there are already documented renal scar or urinary tract abnormality in infection period. Especially upper UTI that involve renal parenchyme may be result in fatal complication. The purpose of this study is analyzing the relationship between acute reactive marker and $^{99m}TC$-DMSA renal scan in upper urinary tract infection. Methods : This study included 56 children admitted at Dankook University Hospital Pediatric Department in Jan. 1995~May. 1998. We analyzed quantatively the results of acute reactive marker(CRP, ESR, WBC), pyuria, fever and compared to those of sonographically find ing and $^{99m}TC$-DMSA renal scan. Comparison between groups were performed by the chi-square (x2) test and a p value of less than 0.05 was considered statistically significant. Results : 1) The number of boys less than 1 year of age was larger than that of girls. But the number of boys more than 1 year of age was reversed. 2) The higher me level of reactive marker (CRP, WBC), the more the probability of upper UTI. 3) The higher fever, the more the probability of upper UTI. 4) The more pyuria, the more probability of upper UTI. 5) The more higher the grade of vesicoureteral reflux, the more probability of upper UTI. 6) $^{99m}TC$-DMSA renal scan is more sensitive and more specific diagnostic tool than renal sonogram. Conclusion : The appearance of an abnormal $^{99m}TC$-DMSA renal scan is correlated with acute reactive marker (CRP, ESR, WBC), fever, pyuria. $^{99m}TC$-DMSA renal scan can be a good valuable predictor tool in upper UTI. So we can start early treatment and decrease the incidence of complication of upper urinary tract by above indicators before knowing the result of urine culture. And we can follow up the patients in more good relationships with their parents by telling them the duration of treatment and follow-up plan.